The utility model discloses an oil shaft temperature detector for a worm and gear speed reducer. The oil temperature measuring device comprises an oil temperature sensor, an infrared temperature measuring device and a case. An oil outlet hole is formed in the side face, close to the bottom end, of the speed reducer and used for installing an oil temperature sensor. The two infrared temperature measuring devices are placed on one side of the driving column and one side of the driven shaft end cover outside the speed reducer respectively, and the infrared temperature measuring sensors are aligned with the centers of the end covers. The number of the temperature sensors is three, the temperature sensors measure the temperature of lubricating oil and the temperature of the two rotating shaftsrespectively, and the output ends of the two sensors are aviation plugs. The case is used for collecting, storing and displaying the temperature of lubricating oil and the temperature of the rotatingshaft, and has an alarm function and three aviation sockets. According to the utility model, shaft oil temperatures of worm and gear speed reducers of different models, even shaft oil temperatures ofdifferent types of speed reducers, can be measured at the same time, and the problem that the lubricating oil temperature and the rotating shaft temperature of a common speed reducer are difficult tomeasure can be effectively solved.